An integrated pharmacokinetic and pharmacodynamic study of a new drug of abuse, methylone, a synthetic cathinone sold as "bath salts"

Simple and selective screening method for the synthetic cathinone MDPT in forensic samples using carbon nanofiber screen-printed electrodes

3',4'-Methylenedioxy-N-tert-butylcathinone (MDPT), also known as tBuONE or D-Tertylone, is a synthetic cathinone (SC) frequently abused for recreational purposes due to its potent stimulant effects and similarity to illegal substances like methamphetamine and ecstasy. The structural diversity and rapid introduction of new SC analogs to the market poses significant challenges for law enforcement and analytical methods for preliminary screening of illicit drugs. In this work, we present, for the first time, the electrochemical detection of MDPT using screen-printed electrodes modified with carbon nanofibers (SPE-CNF). MDPT exhibited three electrochemical processes (two oxidations and one reduction) on SPE-CNF. The proposed method for MDPT detection was optimized in 0.2 mol L-1 Britton-Robinson buffer solution at pH 10.0 using differential pulse voltammetry (DPV). The SPE-CNF showed a high stability for electrochemical responses of all redox processes of MDPT using the same or different electrodes, with relative standard deviations less than 4.7% and 1.5% (N = 3) for peak currents and peak potentials, respectively. Moreover, the proposed method provided a wide linear range for MDPT determination (0.90-112 μmol L-1) with low LOD (0.26 μmol L-1). Interference studies for two common adulterants, caffeine and paracetamol, and ten other illicit drugs, including amphetamine-like compounds and different SCs, showed that the proposed sensor is highly selective for the preliminarily identification of MDPT in seized forensic samples. Therefore, SPE-CNF with DPV can be successfully applied as a fast and simple screening method for MDPT identification in forensic analysis, addressing the significant challenges posed by the structural diversity of SCs.

Cardiovascular and Locomotor Effects of Binary Mixtures of Common "Bath Salts" Constituents: Studies with Methylone, MDPV, and Caffeine in Rats

Background and Purpose

The use of "Bath Salts" drug preparations has been associated with high rates of toxicity and death. Preparations often contain mixtures of drugs including multiple synthetic cathinones or synthetic cathinones and caffeine; however, little is known about whether interactions among "Bath Salts" constituents contribute to the adverse effects often reported in users.

Experimental Approach

This study used adult male Sprague-Dawley rats to characterize the cardiovascular effects, locomotor effects, and pharmacokinetics of methylone, MDPV, and caffeine, administered alone and as binary mixtures. Dose-addition analyses were used to determine the effect levels predicted for a strictly additive interaction for each dose pair.

Key Results

Methylone, MDPV, and caffeine increased heart rate and locomotion, with methylone producing the largest increase in heart rate, MDPV producing the largest increase in locomotor activity, and caffeine being the least effective in stimulating heart rate and locomotor activity. MDPV and caffeine increased mean arterial pressure, with caffeine being more effective than MDPV. The nature of the interactions between methylone and MDPV tended toward sub-additivity for all endpoints, whereas interactions between MDPV or methylone and caffeine tended to be additive or sub-additive for cardiovascular endpoints, and additive or supra-additive for increases in locomotion. No pharmacokinetic interactions were observed between individual constituents, but methylone displayed non-linear pharmacokinetics at the largest dose evaluated.

Conclusion and Implications

These findings demonstrate that the composition of "Bath Salts" preparations can impact both cardiovascular and locomotor effects and suggest that such interactions among constituent drugs could contribute to the "Bath Salts" toxidrome reported by human users.

Methylone produces antidepressant-relevant actions and prosocial effects

Methylone (3,4-methylenedioxy-N-methylcathinone) is a rapid-acting entactogen that has been shown to have significant benefits in patients with post-traumatic stress disorder and major depressive disorder and is well tolerated in phase 1 clinical trials. A recent preclinical study reported that methylone produced robust antidepressant-like actions in naïve rats. However, its antidepressant effects on various stress-related psychopathologies and other neuropsychological actions remain unclear. In the present study, we examined the antidepressant-relevant effects of methylone in learned helplessness (LH) and social defeat stress C57BL/6J male mouse models and further explored its sociability-relevant neuropsychological actions. Our results indicate that methylone produces antidepressant-relevant effects on the helpless phenotype, LH-evoked depressive-like behaviors, and psychosocial stress-induced social avoidance, and induced depressive-like behaviors. In addition, methylone was found to enhance social preference and increase various social behaviors, including social contact, sniffing, allogrooming, and following. Moreover, methylone appeared to elevate empathy-like phenotypes and was also found to increase helping-like behavior. Overall, the present results suggest that methylone plays an antidepressant-like role in various stress-relevant psychopathologies and could be an ideal antidepressant candidate. In addition, novel findings on the elevated tendencies of social preference and empathy-like and helping-like phenotypes reveal that methylone may have potential application in patients with social deficits.

Male and female C57BL/6 mice display drug-induced aversion and reward in the combined conditioned taste avoidance/conditioned place preference procedure

BACKGROUND

Drugs of abuse have rewarding and aversive effects that, in balance, impact abuse potential. Although such effects are generally examined in independent assays (e.g., CPP and CTA, respectively), a number of studies have examined these effects concurrently in rats in a combined CTA/CPP design. The present study assessed if similar effects can be produced in mice which would allow for determining how each is affected by subject and experiential factors relevant to drug use and abuse and the relationship between these affective properties.

METHODS

Male and female C57BL/6 mice were exposed to a novel saccharin solution, injected (IP) with saline or 5.6, 10 or 18 mg/kg of the synthetic cathinone, methylone, and placed on one side of the place conditioning apparatus. The following day, they were injected with saline, given access to water and placed on the other side of the apparatus. After four conditioning cycles, saccharin avoidance and place preferences were assessed in a final two-bottle CTA test and a CPP Post-Test, respectively.

RESULTS

In the combined CTA/CPP design, mice acquired a significant dose-dependent CTA (p = 0.003) and a significant CPP (p = 0.002). These effects were independent of sex (all p's > 0.05). Further, there was no significant relationship between the degree of taste avoidance and place preference (p > 0.05).

CONCLUSIONS

Similar to rats, mice displayed significant CTA and CPP in the combined design. It will be important to extend this design in mice to other drugs and to examine the impact of different subject and experiential factors on these effects to facilitate predictions of abuse liability.

Pharmacological effects of methylone and MDMA in humans

Methylone is one of the most common synthetic cathinones popularized as a substitute for 3,4-methylenedioxymethamphetamine (MDMA, midomafetamine) owing to its similar effects among users. Both psychostimulants exhibit similar chemistry (i.e., methylone is a β-keto analog of MDMA) and mechanisms of action. Currently, the pharmacology of methylone remains scarcely explored in humans. Herein, we aimed to evaluate the acute pharmacological effects of methylone and its abuse potential in humans when compared with that of MDMA following oral administration under controlled conditions. Seventeen participants of both sexes (14 males, 3 females) with a previous history of psychostimulant use completed a randomized, double-blind, placebo-controlled, crossover clinical trial. Participants received a single oral dose of 200 mg of methylone, 100 mg of MDMA, and a placebo. The variables included physiological effects (blood pressure, heart rate, oral temperature, pupil diameter), subjective effects using visual analog scales (VAS), the short form of the Addiction Research Center Inventory (ARCI), the Evaluation of Subjective Effects of Substances with Abuse Potential questionnaire (VESSPA-SSE), and the Sensitivity to Drug Reinforcement Questionnaire (SDRQ), and psychomotor performance (Maddox wing, psychomotor vigilance task). We observed that methylone could significantly increase blood pressure and heart rate and induce pleasurable effects, such as stimulation, euphoria, wellbeing, enhanced empathy, and altered perception. Methylone exhibited an effect profile similar to MDMA, with a faster overall onset and earlier disappearance of subjective effects. These results suggest that abuse potential of methylone is comparable to that of MDMA in humans. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT05488171; Identifier: NCT05488171.

Methylone and MDMA Pharmacokinetics Following Controlled Administration in Humans

The aim of this study is to define, for the first time, human methylone and HMMC plasma pharmacokinetics following controlled administration of 50-200 mg methylone to 12 male volunteers. A new LC-MS/MS method was validated to quantify methylone, MDMA, and their metabolites in plasma. The study was a randomized, cross-over, double-blinded and placebo-controlled study, with a total of 468 plasma samples collected. First, 10 µL of MDMA-d₅, MDA-d₅ and methylone-d₃ internal standards were added to 100 µL of plasma. Two mL of chloroform and ethyl acetate 9:1 (v/v) were then added, mixed well and centrifuged. The supernatant was fortified with 0.1 mL acidified methanol and evaporated under nitrogen. Samples were reconstituted with a mobile phase and injected into the LC-MS/MS instrument. The method was fully validated according to OSAC guidelines (USA). Methylone plasma concentrations increased in a dose-proportional manner, as demonstrated by the increasing maximum concentration (Cmax) and area under the curve of concentrations (AUC). Methylone Cmax values were reported as 153, 304, 355 and 604 ng/mL, AUC0-24 values were reported as 1042.8, 2441.2, 3524.4 and 5067.9 h·ng/mL and T_1/2 values as 5.8, 6.4, 6.9 and 6.4 h following the 50, 100, 150 and 200 mg doses, respectively. Methylone exhibited rapid kinetics with a Tmax of 1.5 h for the 50 mg dose and 2 h approximately after all the other doses. HMMC exhibited faster kinetics compared to methylone, with a Cmax value that was 10-14-fold lower and an AUC0-24 value that was 21-29-fold lower. Methylone pharmacokinetics was linear across 50-200 mg oral doses in humans, unlike the previously described non-linear oral MDMA pharmacokinetics. An LC-MS/MS method for the quantification of methylone, MDMA and their metabolites in human plasma was achieved. Methylone exhibited linear pharmacokinetics in humans with oral doses of 50-200 mg.

Enantioselectivity of Pentedrone and Methylone on Metabolic Profiling in 2D and 3D Human Hepatocyte-like Cells

Pentedrone and methylone can express stereoselectivity in toxicokinetic and toxicodynamic processes. Similarly, their chiral discrimination in metabolism, which was not yet evaluated, can result in different metabolic profiles and subsequent hepatotoxic effects. Therefore, the aim of this work was to assess, for the first time, both the hepatic cytotoxic and metabolic profile of pentedrone and methylone enantiomers using physiologically relevant in vitro models. The hepatotoxicity of these compounds was observed in a concentration-dependent manner in human stem-cell-derived hepatocyte-like cells (HLCs) cultured under 3D (3D-HLCs) and 2D (2D-HLCs) conditions. Enantioselectivity, on the other hand, was only shown for pentedrone (1 mM) in 3D-HLCs, being R-(−)-pentedrone the most cytotoxic. Furthermore, the metabolic profile was initially evaluated in human liver microsomes (HLM) and further demonstrated in 3D-HLCs and 2D-HLCs applying a gas chromatography coupled to a mass spectrometer (GC–MS) technique. Methylone and pentedrone showed distinct and preferential metabolic routes for their enantiomers, resulting in the production of differentiated metabolites; R-(+)-methylone and R-(−)-pentedrone are the most metabolized enantiomers. In conclusion, the results demonstrated enantioselectivity for pentedrone and methylone in the metabolic processes, with enantioselectivity in cytotoxicity for pentedrone.

Methylone, a rapid acting entactogen with robust anxiolytic and antidepressant-like activity

INTRODUCTION

Selective serotonin reuptake inhibitor (SSRI) antidepressants represent first-line pharmacological treatment for a variety of neuropsychiatric illnesses, including major depressive disorder (MDD), anxiety, and post-traumatic stress disorder (PTSD), which show high rates of comorbidity. SSRIs have a delayed onset of action. Most patients do not show significant effects until 4-8 weeks of continuous treatment, have impairing side effects and as many as 40% of patients do not respond. Methylone (3,4-methylenedioxy-N-methylcathinone; MDMC, βk-MDMA, M1) is a rapid-acting entactogen that showed significant benefit in a clinical case series of PTSD patients and was well-tolerated in two Phase 1 studies of healthy volunteers. Based on these early observations in humans, in the current study we tested the hypothesis that methylone has antidepressant-like and anxiolytic effects in preclinical tests.

METHODS

For all studies, 6-8-week-old male Sprague Dawley rats (N = 6-16) were used. We employed the Forced Swim Test (FST), a classic and widely used screen for antidepressants, to explore the effects of methylone and to probe dose-response relationships, durability of effect, and potential interactions with combined SSRI treatment. We compared the effect of methylone with the prototypical SSRI fluoxetine.

RESULTS

Three doses of fluoxetine (10 mg/kg) given within 24 h before FST testing caused a 50% reduction in immobility compared with controls that lasted less than 24 h. In contrast, a single dose of methylone (5-30 mg/kg) administered 30 min prior to testing produced a rapid, robust, and durable antidepressant-like response in the FST, greater in magnitude than fluoxetine. Immobility was reduced by nearly 95% vs. controls and effects persisted for at least 72 h after a single dose (15 mg/kg). Effects on swimming and climbing behavior in the FST, which reflect serotonergic and noradrenergic activity, respectively, were consistent with studies showing that methylone is less serotoninergic than MDMA. Fluoxetine pretreatment did not change methylone's antidepressant-like effect in the FST, suggesting the possibility that the two may be co-administered. In addition, methylone (5-30 mg/kg) exhibited anxiolytic effects measured as increased time spent in the center of an open field.

DISCUSSION

Taken together, and consistent with initial clinical findings, our study suggests that methylone may have potential for treating depression and anxiety.

A Comparison of Acute Pharmacological Effects of Methylone and MDMA Administration in Humans and Oral Fluid Concentrations as Biomarkers of Exposure

Simple Summary

Methylone is a synthetic cathinone that is usually used as a substitute for conventional psychostimulants, such as MDMA. Chemically, methylone is considered the β-keto analogue of MDMA, with which it presumably shares similar pharmacological effects. To date, the available data about the human pharmacology of methylone in humans are very scarce and are mainly derived from user experiences, published in internet forums or intoxication reports. Thus, an observational–naturalistic study was conducted to evaluate the acute pharmacological effects and determine biomarkers of exposure in oral fluid of methylone after oral self-administration in comparison to MDMA. Methylone induced the prototypical psychostimulant and empathogenic effects commonly associated with MDMA, although they were of lower intensity. Oral fluid concentrations of methylone can be considered a suitable biomarker of acute exposure, and oral fluid has been proven to be a useful biological matrix of detection.

Abstract

Considered the β-keto analogue of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy), 3,4-Methylenedioxymethcathinone (methylone) is a synthetic cathinone. Over the years, methylone has been used as a substitute for conventional psychostimulants, such as MDMA. To date, little is known about the human pharmacology of methylone; the only available information has been provided by surveys or published intoxication reports. In the present observational–naturalistic study, we evaluate the acute subjective and physiological effects of methylone after oral self-administration in comparison to MDMA in healthy poly-drug users. Fourteen participants (10 males, 4 females) selected their single oral doses of methylone from 100 to 300 mg (n = 8, mean dose 187.5 mg) or MDMA from 75 to 100 mg (n = 6, mean dose 87.5 mg) based on their experience. Study variables were assessed at 0, 1, 2, and 4 h (h) and included vital signs (non-invasive blood pressure, heart rate, cutaneous temperature) and subjective effects using visual analogue scales (VAS), the 49-item Addiction Research Centre Inventory (ARCI) short form, and the Evaluation of the Subjective Effects of Substances with Abuse Potential (VESSPA-SSE) questionnaire. Additionally, oral fluid concentrations of methylone and MDMA were determined. Acute pharmacological effects produced by methylone followed the prototypical psychostimulant and empathogenic profile associated with MDMA, although they were less intense. Methylone concentrations in oral fluid can be considered a useful biomarker to detect acute exposure in oral fluid. Oral fluid concentrations of MDMA and methylone peaked at 2 h and concentrations of MDMA were in the range of those previously described in controlled studies. Our results demonstrate that the potential abuse liability of methylone is similar to that of MDMA in recreational subjects.

An updated review on synthetic cathinones

Cathinone, the main psychoactive compound found in the plant Catha edulis Forsk. (khat), is a β-keto analogue of amphetamine, sharing not only the phenethylamine structure, but also the amphetamine-like stimulant effects. Synthetic cathinones are derivatives of the naturally occurring cathinone that largely entered the recreational drug market at the end of 2000s. The former "legal status", impressive marketing strategies and their commercial availability, either in the so-called "smartshops" or via the Internet, prompted their large spread, contributing to their increasing popularity in the following years. As their popularity increased, the risks posed for public health became clear, with several reports of intoxications and deaths involving these substances appearing both in the social media and scientific literature. The regulatory measures introduced thereafter to halt these trending drugs of abuse have proved to be of low impact, as a continuous emergence of new non-controlled derivatives keep appearing to replace those prohibited. Users resort to synthetic cathinones due to their psychostimulant properties but are often unaware of the dangers they may incur when using these substances. Therefore, studies aimed at unveiling the pharmacological and toxicological properties of these substances are imperative, as they will provide increased expertise to the clinicians that face this problem on a daily basis. The present work provides a comprehensive review on history and legal status, chemistry, pharmacokinetics, pharmacodynamics, adverse effects and lethality in humans, as well as on the current knowledge of the neurotoxic mechanisms of synthetic cathinones.

Brain Concentrations of Methylone and Its Metabolites after Systemic Methylone Administration: Relationship to Pharmacodynamic Effects

3,4-Methylenedioxy-N-methylcathinone (methylone) is a new psychoactive substance with stimulant properties and potential for abuse. Despite its popularity, limited studies have examined relationships between brain concentrations of methylone, its metabolites, and pharmacodynamic effects. The goal of the present study was 2-fold: 1) to determine pharmacokinetics of methylone and its major metabolites-4-hydroxy-3-methoxy-N-methylcathinone (HMMC), 3,4-dihydroxy-N-methylcathinone (HHMC), and 3,4-methylenedioxycathinone (MDC)-in rat brain and plasma and 2) to relate brain pharmacokinetic parameters to pharmacodynamic effects including locomotor behavior and postmortem neurochemistry. Male Sprague-Dawley rats received subcutaneous methylone (6, 12, or 24 mg/kg) or saline vehicle (n = 16/dose), and subgroups were decapitated after 40 or 120 minutes. Plasma and prefrontal cortex were analyzed for concentrations of methylone and its metabolites by liquid chromatography-tandem mass spectrometry. Frontal cortex and dorsal striatum were analyzed for dopamine, 5-HT, and their metabolites by high-performance liquid chromatography-electrochemical detection. Brain and plasma concentrations of methylone and its metabolites rose with increasing methylone dose, but brain methylone and MDC concentrations were greater than dose-proportional. Brain-to-plasma ratios for methylone and MDC were ≥ 3 (range 3-12), whereas those for HHMC and HMMC were ≤ 0.2 (range 0.01-0.2). Locomotor activity score was positively correlated with brain methylone and MDC, whereas cortical 5-HT was negatively correlated with these analytes at 120 minutes. Our findings show that brain concentrations of methylone and MDC display nonlinear accumulation. Behavioral and neurochemical effects of systemically administered methylone are related to brain concentrations of methylone and MDC but not its hydroxylated metabolites, which do not effectively penetrate into the brain. SIGNIFICANCE STATEMENT: Behavioral and neurochemical effects of methylone are related to brain concentrations of methylone and its metabolite MDC but not its hydroxylated metabolites, 4-hydroxy-3-methoxy-N-methylcathinone and 3,4-dihydroxy-N-methylcathinone, which do not effectively penetrate into the brain. Methylone and MDC display nonlinear accumulation in the brain, which could cause untoward effects on serotonin neurons in vulnerable brain regions, including the frontal cortex.

Assessment of aversive effects of methylone in male and female Sprague-Dawley rats: Conditioned taste avoidance, body temperature and activity/stereotypies

Methylone's rewarding effects have been well characterized; however, little is known about its aversive effects and how such effects may be impacted by sex. In this context, the present study investigated the aversive effects of methylone (vehicle, 5.6, 10 or 18 mg/kg, IP) in 35 male and 31 female Sprague-Dawley rats assessed by conditioned taste avoidance and changes in body temperature and activity/stereotypies. Methylone induced significant taste avoidance, changes in temperature and increased activity and stereotypies in both males and females. Similar to work with other synthetic cathinones, methylone has aversive effects as indexed by significant taste avoidance and changes in temperature and activity (two characteristics of methylone overdose in humans). The only endpoint for which there were significant sex differences was in general activity with males displaying a faster onset and females displaying a longer duration. Although sex was not a factor with taste avoidance and temperature, separate analyses for males and females revealed different patterns, e.g., males displayed a more rapid acquisition of taste avoidance and females displayed changes in temperature at lower doses. Males displayed a faster onset and females displayed a longer duration of activity (consistent with the analyses considering sex as a factor), while time- and dose-dependent stereotypies did not show consistent pattern differences. Although sex differences were relatively limited when sex was specifically assessed as a factor (or only evident when sex comparisons were made in the patterns of effects), sex as a biological variable in the study of drugs should be made to determine if differences exist and, if evident, the basis for these differences.

Understanding the pharmacokinetics of synthetic cathinones: Evaluation of the blood-brain barrier permeability of 13 related compounds in rats

Synthetic cathinones are the second most commonly seized new psychoactive substance family in Europe. These compounds have been related to several intoxication cases, including fatalities. Although the pharmacological effects, metabolism, and pharmacokinetics of cathinones have been studied, there is little information about the permeability of these compounds through the blood-brain barrier (BBB). This is an important parameter to understand the behavior and potency of cathinones. In this work, 13 selected cathinones have been analyzed in telencephalon tissue from Sprague-Dawley rats intraperitoneally dosed at 3 mg/kg. Our results revealed a direct relationship between compound polarity and BBB permeability, with higher permeability for the more polar cathinones. The chemical moieties present in the cathinone had an important impact on the BBB permeability, with lengthening of the α-alkyl chain or functionalization of the aromatic ring with alkyl moieties resulting in lower concentration in telencephalon tissue. Our data suggest that transport of cathinones is a carrier-mediated process, similar to cocaine transport across the BBB.

Hazard Characterization of Synthetic Cathinones Using Viability, Monoamine Reuptake, and Neuronal Activity Assays

Synthetic cathinones are the second largest class of new psychoactive substances (NPS) on the drug market. Despite the large number of different cathinones and their abundant use, hazard characterization is mainly limited to their potential to inhibit monoamine transporters. To expand the current hazard characterization, we first investigated the acute effects of several synthetic cathinones [4-methylethcathinone (4-MEC), 3-methylmethcathinone (3-MMC), 4-MMC, methylone, pentedrone, α-pyrrolidinovalerophenone (α-PVP), and 3,4-methylenedioxypyrovalerone (MDPV)] on human dopamine, norepinephrine, and serotonin reuptake transporters (hDAT, hNET, and hSERT), which were stably transfected in human embryonic kidney (HEK) 293 cells. Next, we examined effects on spontaneous neuronal activity in rat primary cortical cultures grown on microelectrode arrays (MEAs) as an integrated endpoint for neurotoxicity. Changes in neuronal activity were assessed after acute (30 min) and prolonged (4.5 h) exposure. Moreover, we investigated whether neuronal activity recovered after washout of the exposure (24 h after the start of the 5 h exposure). Low micromolar concentrations of synthetic cathinones inhibited monoamine uptake via hDAT and hNET, while higher cathinone concentrations were needed to inhibit uptake via hSERT. Comparable high concentrations were needed to inhibit spontaneous neuronal activity during acute (30 min) and prolonged (4.5 h) exposure. Notably, while the inhibition of neuronal activity was reversible at low concentrations, only partial recovery was seen following high, but non-cytotoxic, concentrations of synthetic cathinones. Synthetic cathinones with either a pyrrolidine moiety or long alkyl-tail carbon chain more potently inhibit monoamine uptake via hDAT and neuronal activity. Monoamine uptake via hNET was most potently inhibited by synthetic cathinones with a pyrrolidine moiety. The combination of integrated measurements (MEA recordings of neuronal activity) with single target assays (monoamine reuptake transporter inhibition) indicates inhibition of hDAT and hNET as the primary mode of action of these synthetic cathinones. Changes in neuronal activity, indicative for additional mechanisms, were observed at higher concentrations.

Metabolites of the ring-substituted stimulants MDMA, methylone and MDPV differentially affect human monoaminergic systems

BACKGROUND

Amphetamine analogs with a 3,4-methylenedioxy ring-substitution are among the most popular illicit drugs of abuse, exerting stimulant and entactogenic effects. Enzymatic N-demethylation or opening of the 3,4-methylenedioxy ring via O-demethylenation gives rise to metabolites that may be pharmacologically active. Indeed, previous studies in rats show that specific metabolites of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxypyrovalerone (MDPV) can interact with monoaminergic systems.

AIM

Interactions of metabolites of MDMA, methylone and MDPV with human monoaminergic systems were assessed.

METHODS

The ability of parent drugs and their metabolites to inhibit uptake of tritiated norepinephrine, dopamine and serotonin (5-HT) was assessed in human embryonic kidney 293 cells transfected with human monoamine transporters. Binding affinities and functional activity at monoamine transporters and various receptor subtypes were also determined.

RESULTS

MDMA and methylone displayed greater potency to inhibit norepinephrine uptake as compared to their effects on dopamine and 5-HT uptake. N-demethylation of MDMA failed to alter uptake inhibition profiles, whereas N-demethylation of methylone decreased overall transporter inhibition potencies. O-demethylenation of MDMA, methylone and MDPV resulted in catechol metabolites that maintained norepinephrine and dopamine uptake inhibition potencies, but markedly reduced activity at 5-HT uptake. O-methylation of the catechol metabolites significantly decreased norepinephrine uptake inhibition, resulting in metabolites lacking significant stimulant properties.

CONCLUSIONS

Several metabolites of MDMA, methylone and MDPV interact with human transporters and receptors at pharmacologically relevant concentrations. In particular, N-demethylated metabolites of MDMA and methylone circulate in unconjugated form and could contribute to the in vivo activity of the parent compounds in human users.

A review of the influence of functional group modifications to the core scaffold of synthetic cathinones on drug pharmacokinetics

RATIONALE

The synthetic cathinones are a class of designer drugs of abuse that share a common core scaffold. The pharmacokinetic profiles of the synthetic cathinones vary based on the substitutions to the core scaffold.

OBJECTIVES

To provide a summary of the literature regarding the pharmacokinetic characteristics of the synthetic cathinones, with a focus on the impact of the structural modifications to the pharmacokinetics.

RESULTS

In many, but not all, instances the pharmacokinetic characteristics of the synthetic cathinones can be reasonably predicted based on the substitutions to the core scaffold. Mephedrone and methylone are chemically alike and have similar T_max and t_1/2 in male rats. MDPV, a structurally distinct synthetic cathinone from mephedrone and methylone, has a lower T_max and t_1/2. Increasing the length of the alkyl chain on the α position of methylone, to produce pentylone, results in increased plasma concentrations and longer t_1/2. Metabolism of the synthetic cathinones is reasonably predictable based on the chemical structure, and several phase I metabolites retain pharmacodynamic activity. CYP2D6 is implicated in the metabolism of all of the synthetic cathinones, and other P450s (CYP1A2, CYP2B6, and CYP2C19) are known to contribute variably to the metabolism of specific synthetic cathinones.

CONCLUSIONS

Continued research will lead to a better understanding of the pharmacokinetic changes associated with structural modifications to the cathinone scaffold, and potentially in the long range, enhanced overdose and addiction therapy. Additionally, the areas of polydrug use and pharmacogenetics have been largely overlooked with regard to synthetic cathinones.

Wastewater-based epidemiology in low Human Development Index states: bias in consumption monitoring of illicit drugs

Wastewater-based epidemiology is a promising approach worldwide, and its application is currently being developed in non-advanced economies. This technology, based on known toxicokinetic data initially used to detect illicit drugs in well-managed and maintained local sewer networks, has been extended to assess other products such as pesticides, alcohol, flame retardants, nicotine, and other substances. This technology is also used in countries with non-advanced economies. The present review aims to support future wastewater-based epidemiology in such countries by providing toxicokinetic data for locally used narcotic drugs that are expected or known to be emerging in developed countries, outlining the excretion differences due to human polymorphism, and summarising the practical obstacles due to the coverage, maintenance efficiency, or type of local sewage network.Case study feedback from Martinique is presented as an example; the Martinique field study complies with the Organisation for Economic Co-operation and Development standards for health issues, but not with regard to population and urban dynamics.

Identification of three new phase II metabolites of a designer drug methylone formed in rats by N-demethylation followed by conjugation with dicarboxylic acids

1. Methylone (3,4-methylenedioxy-N-methylcathinone, MDMC), which appeared on the illicit drug market in 2004, is a frequently abused synthetic cathinone derivative. Known metabolic pathways of MDMC include N-demethylation to normethylone (3,4-methylenedioxycathinone, MDC), aliphatic chain hydroxylation and oxidative demethylenation followed by monomethylation and conjugation with glucuronic acid and/or sulphate. 2. Three new phase II metabolites, amidic conjugates of MDC with succinic, glutaric and adipic acid, were identified in the urine of rats dosed subcutaneously with MDMC.HCl (20 mg/kg body weight) by LC-ESI-HRMS using synthetic reference standards to support identification. 3. The main portion of administered MDMC was excreted unchanged. Normethylone, was a major urinary metabolite, of which a minor part was conjugated with dicarboxylic acids. 4. Previously identified ring-opened metabolites 4-hydroxy-3-methoxymethcathinone (4-OH-3-MeO-MC), 3-hydroxy-4-methoxymeth-cathinone (3-OH-4-MeO-MC) and 3,4-dihydroxymethcathinone (3,4-di-OH-MC) mostly in conjugated form with glucuronic and/or sulphuric acids were also detected. 5. Also, ring-opened metabolites derived from MDC, namely, 4-hydroxy-3-methoxycathinone (4-OH-3-MeO-C), 3-hydroxy-4-methoxycathinone (3-OH-4-MeO-C) and 3,4-dihydroxycathinone (3,4-di-OH-C) were identified for the first time in vivo.

Neurotoxicology of Synthetic Cathinone Analogs

The present review briefly explores the neurotoxic properties of methcathinone, mephedrone, methylone, and methylenedioxypyrovalerone (MDPV), four synthetic cathinones most commonly found in "bath salts." Cathinones are β-keto analogs of the commonly abused amphetamines and display pharmacological effects resembling cocaine and amphetamines, but despite their commonalities in chemical structures, synthetic cathinones possess distinct neuropharmacological profiles and produce unique effects. Among the similarities of synthetic cathinones with their non-keto analogs are their targeting of monoamine systems, the release of neurotransmitters, and their stimulant properties. Most of the literature on synthetic cathinones has focused on describing their properties as psychostimulants, their behavioral effects on locomotion, memory, and potential for abuse, whereas descriptions of their neurotoxic properties are not abundant. The biochemical gauges of neurotoxicity induced by non-keto analogs are well studied in humans and experimental animals and include their ability to induce neuroinflammation, oxidative stress, excitotoxicity, temperature alterations as well as dysregulation of neurotransmitter systems and induce changes in monoamine transporters and receptors. These neurotoxicity gauges will serve as parameters to discuss the effects of the four previously mentioned synthetic cathinones alone or in combination with either another cathinone or with some of their non-keto analogs. Bath salts are not a defined combination of drugs and may consist of one synthetic cathinone compound or combinations of more cathinones. Furthermore, this review also presents some of the mechanisms that are thought to underlie this toxicity. A better understanding of the cellular and molecular mechanisms involved in the synthetic cathinones-induced neurotoxicity should contribute to generate modern therapeutic approaches to prevent or attenuate the adverse consequences of use of these drugs in humans.

Impact of common clandestine structural modifications on synthetic cathinone "bath salt" pharmacokinetics

Since 2009, the synthetic cathinones ("bath salts") have risen in popularity as drugs of abuse. However, there are a paucity of studies that have determined the impact of functional group modifications in the synthetic cathinone chemical structures on plasma and central nervous system (CNS) pharmacokinetics. In the present study, we investigated the in vivo plasma and CNS pharmacokinetics of three synthetic cathinones whose structures differ by lengthening of the α-alkyl chain: methylone (-CH₃), butylone (-CH₂CH₃), and pentylone (-CH₂CH₂CH₃). Male Sprague-Dawley rats were treated with a 20mg/kg subcutaneous dose of the individual synthetic cathinone. Blood samples were obtained at specific times from a jugular vein cannula over an 8hour period. Over a separate three-hour period, CNS samples were obtained using a microdialysis cannula surgically implanted into the lateral ventricle. In the plasma, pentylone, with the longest α-alkyl chain, displayed the highest C_max and AUC_0-∞, and the longest t_1/2. Decreasing the α-alkyl chain length as in butylone and methylone significantly decreased the C_max, AUC_0-∞, and t_1/2. The plasma pharmacokinetic values are consistent with the greater lipophilicity associated with α-alkyl side chain lengthening. Conversely, in the CNS, methylone and butylone displayed higher C_max and AUC_0-∞ values than pentylone. These contrary findings in the CNS and plasma demonstrate that lengthening of the α-alkyl chain of methylone, butylone, and pentylone yields differential pharmacokinetic properties in the CNS as compared to the plasma.

Pharmacokinetic Profiles and Pharmacodynamic Effects for Methylone and Its Metabolites in Rats

3,4-Methylenedioxy-N-methylcathinone (methylone) is a new psychoactive substance and the β-keto analog of 3,4-methylenedioxy-N-methylamphetamine (MDMA). It is well established that MDMA metabolism produces bioactive metabolites. Here we tested the hypothesis that methylone metabolism in rats can form bioactive metabolites. First, we examined the pharmacokinetics (PKs) of methylone and its metabolites after subcutaneous (sc) methylone administration (3, 6, 12 mg/kg) to male rats fitted with intravenous (iv) catheters for repeated blood sampling. Plasma specimens were assayed by liquid chromatography tandem mass spectrometry to quantify methylone and its phase I metabolites: 3,4-methylenedioxycathinone (MDC), 3,4-dihydroxy-N-methylcathinone (HHMC), and 4-hydroxy-3-methoxy-N-methylcathinone (HMMC). The biological activity of methylone and its metabolites was then compared using in vitro transporter assays and in vivo microdialysis in rat nucleus accumbens. For the PK study, we found that methylone and MDC peaked early (T_max=15-45 min) and were short lived (t_1/2=60-90 min), while HHMC and HMMC peaked later (T_max=60-120 min) and persisted (t_1/2=120-180 min). Area-under-the-curve values for methylone and MDC were greater than dose-proportional, suggesting non-linear accumulation. Methylone produced significant locomotor activation, which was correlated with plasma methylone, MDC, and HHMC concentrations. Methylone, MDC, and HHMC were substrate-type releasers at monoamine transporters as determined in vitro, but only methylone and MDC (1, 3 mg/kg, iv) produced significant elevations in brain extracellular dopamine and 5-HT in vivo. Our findings demonstrate that methylone is extensively metabolized in rats, but MDC is the only centrally active metabolite that could contribute to overall effects of the drug in vivo.

Predicting the Abuse Liability of Entactogen-Class, New and Emerging Psychoactive Substances via Preclinical Models of Drug Self-administration

Animal models of drug self-administration are currently the gold standard for making predictions regarding the relative likelihood that a recreational drug substance will lead to continued use and addiction. Such models have been found to have high predictive accuracy and discriminative validity for a number of drug classes including ethanol, nicotine, opioids, and psychostimulants such as cocaine and methamphetamine. Members of the entactogen class of psychostimulants (drugs that produce an "open mind state" including feelings of interpersonal closeness, intimacy and empathy) have been less frequently studied in self-administration models. The prototypical entactogen 3,4-methylenedioxymethamphetamine (MDMA; "Ecstasy") supports self-administration but not with the same consistency nor with the same efficacy as structurally related drugs amphetamine or methamphetamine. Consistent with these observations, MDMA use is more episodic in the majority of those who use it frequently. Nevertheless, substantial numbers of MDMA users will meet the criteria for substance dependence at some point in their use history. This review examines the currently available evidence from rodent self-administration studies of MDMA and two of the new and emerging psychoactive substances (NPS) that produce entactogen type neuropharmacological responses - mephedrone (4-methylmethcathinone; 4MMC; "meow meow") and methylone (3,4-methylenedioxymethcathinone). Overall, the current evidence predicts that these NPS entactogens have enhanced abuse liability compared with MDMA.

Reinforcing Effects of Cathinone NPS in the Intravenous Drug Self-Administration Paradigm

Since the mid- to late 2000s, there has been a dramatic rise in the use and abuse of synthetic derivatives of cathinone, a stimulant alkaloid found in the African shrub Catha edulis. Cathinone novel psychoactive substances (NPS), also referred to as synthetic cathinones or "bath salt"-type drugs, have gained popularity among drug users due to their potency, low cost, ease of procurement, and diverse array of evolving chemical structures. While the ability of cathinone NPS to produce psychotomimetic effects, multiple organ system toxicity, and death in humans is well documented, there has been limited scientific investigation into the reinforcing effects and abuse liability of these drugs. In this chapter, we will summarize the existing literature on the reinforcing effects of cathinone NPS in rodents using the intravenous self-administration (IVSA) paradigm. We will also compare the ability of cathinone NPS to serve as reinforcers to that of classical psychostimulants such as cocaine, methamphetamine, and methylenedioxymethamphetamine (MDMA). The chapter will conclude with a summary and indications for future avenues of research on cathinone NPS.

Pharmacokinetic, Ambulatory, and Hyperthermic Effects of 3,4-Methylenedioxy-N-Methylcathinone (Methylone) in Rats

Methylone (3,4-methylenedioxy-N-methylcathinone) is a synthetic cathinone analog of the recreational drug ecstasy. Although it is marketed to recreational users as relatively safe, fatalities due to hyperthermia, serotonin syndrome, and multi-organ system failure have been reported. Since psychopharmacological data remain scarce, we have focused our research on pharmacokinetics, and on a detailed evaluation of temporal effects of methylone and its metabolite nor-methylone on behavior and body temperature in rats. Methylone [5, 10, 20, and 40 mg/kg subcutaneously (s.c.)] and nor-methylone (10 mg/kg s.c.) were used in adolescent male Wistar rats across three behavioral/physiological procedures and in two temporal windows from administration (15 and 60 min) in order to test: locomotor effects in the open field, sensorimotor gating in the test of prepulse inhibition (PPI), and effects on rectal temperature in individually and group-housed rats. Serum and brain pharmacokinetics after 10 mg/kg s.c. over 8 h were analyzed using liquid chromatography mass spectrometry. Serum and brain levels of methylone and nor-methylone peaked at 30 min after administration, both drugs readily penetrated the brain with serum: brain ratio 1:7.97. Methylone dose-dependently increased overall locomotion. It also decrease the amount of time spent in the center of open field arena in dose 20 mg/kg and additionally this dose induced stereotyped circling around the arena walls. The maximum of effects corresponded to the peak of its brain concentrations. Nor-methylone had approximately the same behavioral potency. Methylone also has weak potency to disturb PPI. Behavioral testing was not performed with 40 mg/kg, because it was surprisingly lethal to some animals. Methylone 10 and 20 mg/kg s.c. induced hyperthermic reaction which was more pronounced in group-housed condition relative to individually housed rats. To conclude, methylone increased exploration and/or decreased anxiety in the open field arena and with nor-methylone had short duration of action with effects typical for mixed indirect dopamine-serotonin agonists such as 3,4-metyhlenedioxymethamphetamine (MDMA) or amphetamine. Given the fact that the toxicity was even higher than the known for MDMA and that it can cause hyperthermia it possess a threat to users with the risk for serotonin syndrome especially when used in crowded conditions.

The Toxicology of New Psychoactive Substances: Synthetic Cathinones and Phenylethylamines

BACKGROUND

New psychoactive substances (NPSs) are substitutes for classical drugs of abuse and there are now compounds available from all groups of classical drugs of abuse. During 2014, the number of synthetic cathinones increased dramatically and, together with phenylethylamines, they dominate the NPS markets in the European Union. In total, 31 cathinones and 9 phenylethylamines were encountered in 2014. The aim of this article was to summarize the existing knowledge about the basic pharmacology, metabolism, and human toxicology of relevant synthetic cathinones and phenylethylamines. Compared with existing reviews, we have also compiled the existing case reports from both fatal and nonfatal intoxications.

METHODS

We performed a comprehensive literature search using bibliographic databases PubMed and Web of Science, complemented with Google Scholar. The focus of the literature search was on original articles, case reports, and previously published review articles published in 2014 or earlier.

RESULTS

The rapid increase of NPSs is a growing concern and sets new challenges not only for societies in drug prevention and legislation but also in clinical and forensic toxicology. In vivo and in vitro studies have demonstrated that the pharmacodynamic profile of cathinones is similar to that of other psychomotor stimulants. Metabolism studies show that cathinones and phenylethylamines are extensively metabolized; however, the parent compound is usually detectable in human urine. In vitro studies have shown that many cathinones and phenylethylamines are metabolized by CYP2D6 enzymes. This indicates that these drugs may have many possible drug-drug interactions and that genetic polymorphism may influence their toxicity. However, the clinical and toxicological relevance of CYP2D6 in adverse effects of cathinones and phenylethylamines is questionable, because these compounds are metabolized by other enzymes as well. The toxidromes commonly encountered after ingestion of cathinones and phenylethylamines are mainly of sympathomimetic and hallucinogenic character with a risk of excited delirium and life-threatening cardiovascular effects.

CONCLUSIONS

The acute and chronic toxicity of many NPSs is unknown or very sparsely investigated. There is a need for evidence-based-treatment recommendations for acute intoxications and a demand for new strategies to analyze these compounds in clinical and forensic cases.

Synthetic cathinone pharmacokinetics, analytical methods, and toxicological findings from human performance and postmortem cases

Synthetic cathinones are commonly abused novel psychoactive substances (NPS). We present a comprehensive systematic review addressing in vitro and in vivo synthetic cathinone pharmacokinetics, analytical methods for detection and quantification in biological matrices, and toxicological findings from human performance and postmortem toxicology cases. Few preclinical administration studies examined synthetic cathinone pharmacokinetic profiles (absorption, distribution, metabolism, and excretion), and only one investigated metabolite pharmacokinetics. Synthetic cathinone metabolic profiling studies, primarily with human liver microsomes, elucidated metabolite structures and identified suitable biomarkers to extend detection windows beyond those provided by parent compounds. Generally, cathinone derivatives underwent ketone reduction, carbonylation of the pyrrolidine ring, and oxidative reactions, with phase II metabolites also detected. Reliable analytical methods are necessary for cathinone identification in biological matrices to document intake and link adverse events to specific compounds and concentrations. NPS analytical methods are constrained in their ability to detect new emerging synthetic cathinones due to limited commercially available reference standards and continuous development of new analogs. Immunoassay screening methods are especially affected, but also gas-chromatography and liquid-chromatography mass spectrometry confirmation methods. Non-targeted high-resolution-mass spectrometry screening methods are advantageous, as they allow for retrospective data analysis and easier addition of new synthetic cathinones to existing methods. Lack of controlled administration studies in humans complicate interpretation of synthetic cathinones in biological matrices, as dosing information is typically unknown. Furthermore, antemortem and postmortem concentrations often overlap and the presence of other psychoactive substances are typically found in combination with cathinones derivatives, further confounding result interpretation.

Linear pharmacokinetics of 3,4-methylenedioxypyrovalerone (MDPV) and its metabolites in the rat: relationship to pharmacodynamic effects

3,4-Methylenedioxypyrovalerone (MDPV) is a commonly abused synthetic cathinone in the United States and is associated with dangerous side effects. MDPV is a dopamine transporter blocker that is 10-fold more potent than cocaine as a locomotor stimulant in rats. Previous in vitro and in vivo metabolism studies identified 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) as the two primary MDPV metabolites. This study examined MDPV pharmacokinetics and metabolism, along with associated pharmacodynamic effects in rats receiving 0.5, 1.0 and 2.0 mg/kg subcutaneous (s.c.) MDPV. Blood was collected by an indwelling jugular catheter before dosing and at 10, 20, 30, 60, 120, 240 and 480 minutes thereafter. Plasma specimens were analyzed by liquid chromatography coupled to high-resolution tandem mass spectrometry. Maximum concentrations (Cmax ) and area-under-the-curve (AUC) for MDPV and two metabolites increased proportionally with administered dose, showing linear pharmacokinetics. MDPV exhibited the highest Cmax at all doses (74.2-271.3 μg/l) and 4-OH-3-MeOH-PV the highest AUC (11 366-47 724 minutes per μg/l), being the predominant metabolite. MDPV time to Cmax (Tmax ) was 12.9-18.6 minutes, while 3,4-catechol-PV and 4-OH-3-MeO-PV peaked later with Tmax 188.6-240 minutes after s.c. dosing. Horizontal locomotor activity (HLA) and stereotypy correlated positively with plasma MDPV concentrations, while HLA correlated negatively with MDPV metabolites. These results suggest that the parent compound mediates motor stimulation after systemic MDPV administration, but additionally, metabolites may be inhibitory, may not be active or may not pass the blood brain barrier.

Cathinone neurotoxicity ("The "3Ms")

Synthetic cathinones are designer drugs of the phenethylamine class, structurally and pharmacologically similar to amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), cathinone and other related substances. New analogues, legal at least, until formally banned (a time consuming process), are introduced almost daily The United Nations estimates nearly 250 new drug analogues are produced per year. Various combinations of these drugs are sold under the name of “bath salts”. They can be ingested by any route and some appear capable of causing great harm, mostly behavioral. One drug in particular, MDVP, appears to frequently cause symptoms indistinguishable from the classic findings in Excited Delirium Syndrome (ExDS). Little is known about the pathology or clinical toxicology of these drugs but their molecular mechanism of action seems to be identical with that of cocaine. This mini-review examines what little is known on the subject and explains the suspected mechanisms of excited delirium syndrome.

Concentrations of MDPV in rat striatum correlate with the psychostimulant effect

3,4-methylenedioxypyrovalerone or MDPV is a synthetic cathinone with psychostimulant properties more potent than cocaine. We quantified this drug in the striatum after subcutaneous administration to rats. MDPV reached the brain around 5 min after its administration and peaked at 20-25 min later. The elimination half-life in the striatum (61 min) correlates with the decrease in the psychostimulant effect after 60 min. Around 11% of the administered dose reached the striatum and, considering a homogeneous brain distribution, we determined that around 86% of the plasma MDPV is distributed to the brain. MDPV induced a dose-dependent increase in locomotor activity, rearing behaviour and stereotypies, all prevented by haloperidol. A plot of locomotor activity or stereotypies versus MDPV striatal concentrations over time showed a direct relationship between factors. No free MDPV metabolites were detected in plasma, at any time, but hydrolysis with glucuronidase allowed us to identify mainly three metabolites, one of them for the first time in rat plasma. The present results contribute to evidence that MDPV induces hyperlocomotion mainly through a dopamine-dependent mechanism. Good correlation between behavioural effects and striatal levels of MDPV leads us to conclude that its psychostimulant effect is mainly due to a striatal distribution of the substance. The present research provides useful information on the pharmacokinetics of MDPV, and can help design new experiments with kinetics data as well as provide a better understanding of the effects of MDPV in humans and its potential interactions.

The new psychoactive substances 5-(2-aminopropyl)indole (5-IT) and 6-(2-aminopropyl)indole (6-IT) interact with monoamine transporters in brain tissue

In recent years, use of psychoactive synthetic stimulants has grown rapidly. 5-(2-Aminopropyl)indole (5-IT) is a synthetic drug associated with a number of fatalities, that appears to be one of the newest 3,4-methylenedioxymethamphetamine (MDMA) replacements. Here, the monoamine-releasing properties of 5-IT, its structural isomer 6-(2-aminopropyl)indole (6-IT), and MDMA were compared using in vitro release assays at transporters for dopamine (DAT), norepinephrine (NET), and serotonin (SERT) in rat brain synaptosomes. In vivo pharmacology was assessed by locomotor activity and a functional observational battery (FOB) in mice. 5-IT and 6-IT were potent substrates at DAT, NET, and SERT. In contrast with the non-selective releasing properties of MDMA, 5-IT displayed greater potency for release at DAT over SERT, while 6-IT displayed greater potency for release at SERT over DAT. 5-IT produced locomotor stimulation and typical stimulant effects in the FOB similar to those produced by MDMA. Conversely, 6-IT increased behaviors associated with 5-HT toxicity. 5-IT likely has high abuse potential, which may be somewhat diminished by its slow onset of in vivo effects, whereas 6-IT may have low abuse liability, but enhanced risk for adverse effects. Results indicate that subtle differences in the chemical structure of transporter ligands can have profound effects on biological activity. The potent monoamine-releasing actions of 5-IT, coupled with its known inhibition of MAO A, could underlie its dangerous effects when administered alone, and in combination with other monoaminergic drugs or medications. Consequently, 5-IT and related compounds may pose substantial risk for abuse and serious adverse effects in human users.

Identification of polymorphism in ethylone hydrochloride: synthesis and characterization

Ethylone, a synthetic cathinone with psychoactive properties, is a designer drug which has appeared on the recreational drug market in recent years. Since 2012, illicit shipments of ethylone hydrochloride have been intercepted with increasing frequency at the Canadian border. Analysis has revealed that ethylone hydrochloride exists as two distinct polymorphs. In addition, several minor impurities were detected in some seized exhibits. In this study, the two conformational polymorphs of ethylone hydrochloride have been synthesized and fully characterized by FTIR, FT-Raman, powder XRD, GC-MS, ESI-MS/MS and NMR ((13) C CPMAS, (1) H, (13) C). The two polymorphs can be distinguished by vibrational spectroscopy, solid-state nuclear magnetic resonance spectroscopy and X-ray diffraction. The FTIR data are applied to the identification of both polymorphs of ethylone hydrochloride (mixed with methylone hydrochloride) in a laboratory submission labelled as 'Ocean Snow Ultra'. The data presented in this study will assist forensic scientists in the differentiation of the two ethylone hydrochloride polymorphs. This report, alongside our recent article on the single crystal X-ray structure of a second polymorph of this synthetic cathinone, is the first to confirm polymorphism in ethylone hydrochloride. © 2015 Canada Border Services Agency. Drug Testing and Analysis published by John Wiley & Sons, Ltd. © 2015 Canada Border Services Agency. Drug Testing and Analysis published by John Wiley & Sons, Ltd.

Simultaneous determination of four designer drugs and their major metabolites by liquid chromatography-mass spectrometry

A sensitive liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ITMS) method was utilized for the simultaneous analysis of four designer drugs and their in vitro metabolites in rat liver microsome S9 fraction. Four designer drugs, including methcathinone (MC), 3,4-methylenedioxymethcathinone (MDMC), 3,4-methylenedioxy-pyrovalerone (MDPV) and 4'-methyl-α-pyrrolidinopropiophenone (MPPP), were individually incubated with rat liver microsome S9 fraction, and the incubation mixtures were pooled together and analyzed by LC-ESI-ITMS simultaneously. Besides four designer drugs, five of their main metabolites were identified via the analysis of protonated molecules and tandem mass spectrometry data. Meanwhile, the quantification analysis of four designer drugs in rat liver microsome S9 fraction was performed, the calibration curves showed good linearity in the range of 0.01-5.0μg/mL and the detection limits were below 0.03μg/mL with RSDs less than 5.9% and recovery ratios above 77.4%. The experimental results not only showed that these designer drugs could be easily metabolized in rat liver microsome, and also displayed the superiorities of the method including time and cost saving, high efficiency, sensitivity and selectivity. The studies in this study indicated that the approach could be applied in the determination of illicit drugs and their metabolites in medical, pharmaceutical and forensic investigations.

Baths salts, spice, and related designer drugs: the science behind the headlines

The abuse of synthetic psychoactive substances known as "designer drugs," or "new psychoactive substances" (NPS), is increasing at an alarming rate. NPS are purchased as alternatives to traditional illicit drugs of abuse and are manufactured to circumvent laws regulating the sale and use of controlled substances. Synthetic cathinones (i.e., "bath salts") and synthetic cannabinoids (i.e., "spice") are two types of NPS that have received substantial media attention. Although low recreational doses of bath salts or spice compounds can produce desirable effects, high doses or chronic exposure often leads to dangerous medical consequences, including psychosis, violent behaviors, tachycardia, hyperthermia, and even death. Despite the popularity of NPS, there is a paucity of scientific data about these drugs. Here we provide a brief up-to-date review describing the mechanisms of action and neurobiological effects of synthetic cathinones and cannabinoids.

Serotonergic impairment and memory deficits in adolescent rats after binge exposure of methylone

Methylone is a cathinone derivative that has recently emerged as a designer drug of abuse in Europe and the USA. Studies on the acute and long-term neurotoxicity of cathinones are starting to be conducted. We investigated the neurochemical/enzymatic changes indicative of neurotoxicity after methylone administration (4 × 20 mg/kg, subcutaneously, per day with 3 h intervals) to adolescent rats, to model human recreational use. In addition, we studied the effect of methylone on spatial learning ad memory using the Morris water maze paradigm. Our experiments were carried out at a high ambient temperature to simulate the hot conditions found in dance clubs where the drug is consumed. We observed a hyperthermic response to methylone that reached a peak 30 min after each dose. We determined a serotonergic impairment in methylone-treated rats, especially in the frontal cortex, where it was accompanied by astrogliosis. Some serotonergic alterations were also present in the hippocampus and striatum. No significant neurotoxic effect on the dopaminergic system was identified. Methylone-treated animals only displayed impairments in the probe trial of the Morris water maze, which concerns reference memory, while the spatial learning process seemed to be preserved.

Repeated doses of methylone, a new drug of abuse, induce changes in serotonin and dopamine systems in the mouse

RATIONALE

Methylone, a new drug of abuse sold as "bath salts," has similar effects to ecstasy or cocaine.

OBJECTIVE

We have investigated changes in dopaminergic and serotoninergic markers, indicative of neuronal damage induced by methylone in the frontal cortex, hippocampus, and striatum of mice, according to two different treatment schedules.

METHODS

Methylone was given subcutaneously to male Swiss CD1 mice at an ambient temperature of 26 °C. Treatment A consisted of three doses of 25 mg/kg at 3.5-h intervals between doses for two consecutive days, and treatment B consisted of four doses of 25 mg/kg at 3-h intervals in 1 day.

RESULTS

Repeated methylone administration induced hyperthermia and a significant loss in body weight. Following treatment A, methylone induced transient dopaminergic (frontal cortex) and serotoninergic (hippocampus) impairment. Following treatment B, transient dopaminergic (frontal cortex) and serotonergic (frontal cortex and hippocampus) changes 7 days after treatment were found. We found evidence of astrogliosis in the CA1 and the dentate gyrus of the hippocampus following treatment B. The animals also showed an increase in immobility time in the forced swim test, pointing to a depressive-like behavior. In cultured cortical neurons, methylone (for 24 and 48 h) did not induce a remarkable cytotoxic effect.

CONCLUSIONS

The neural effects of methylone differ depending upon the treatment schedule. Neurochemical changes elicited by methylone are apparent when administered at an elevated ambient temperature, four times per day at 3-h intervals, which is in accordance with its short half-life.

Emerging drugs of abuse: current perspectives on substituted cathinones

Substituted cathinones are synthetic analogs of cathinone that can be considered as derivatives of phenethylamines with a beta-keto group on the side chain. They appeared in the recreational drug market in the mid-2000s and now represent a large class of new popular drugs of abuse. Initially considered as legal highs, their legal status is variable by country and is rapidly changing, with government institutions encouraging their control. Some cathinones (such as diethylpropion or pyrovalerone) have been used in a medical setting and bupropion is actually indicated for smoking cessation. Substituted cathinones are widely available from internet websites, retail shops, and street dealers. They can be sold under chemical, evocative or generic names, making their identification difficult. Fortunately, analytical methods have been developed in recent years to solve this problem. Available as powders, substituted cathinones are self-administered by snorting, oral injestion, or intravenous injection. They act as central nervous system stimulants by causing the release of catecholamines (dopamine, noradrenaline, and serotonin) and blocking their reuptake in the central and peripheral nervous system. They may also decrease dopamine and serotonin transporter function as nonselective substrates or potent blockers and may inhibit monoamine oxidase effects. Nevertheless, considerable differences have been found in the potencies of the different substituted cathinones in vitro. Desired effects reported by users include increased energy, empathy, and improved libido. Cardiovascular (tachycardia, hypertension) and psychiatric/neurological signs/symptoms (agitation, seizures, paranoia, and hallucinations) are the most common adverse effects reported. Severe toxicity signs compatible with excessive serotonin activity, such as hyperthermia, metabolic acidosis, and prolonged rhabdomyolysis, have also been observed. Reinforcing potential observed in animals predicts a high potential for addiction and abuse in users. In case of overdose, no specific antidote exists and no curative treatment has been approved by health authorities. Therefore, management of acute toxic effects is mainly extrapolated from experience with cocaine/amphetamines.

Using cheminformatics to predict cross reactivity of "designer drugs" to their currently available immunoassays

Background

A challenge for drug of abuse testing is presented by ‘designer drugs’, compounds typically discovered by modifications of existing clinical drug classes such as amphetamines and cannabinoids. Drug of abuse screening immunoassays directed at amphetamine or methamphetamine only detect a small subset of designer amphetamine-like drugs, and those immunoassays designed for tetrahydrocannabinol metabolites generally do not cross-react with synthetic cannabinoids lacking the classic cannabinoid chemical backbone. This suggests complexity in understanding how to detect and identify whether a patient has taken a molecule of one class or another, impacting clinical care.

Methods

Cross-reactivity data from immunoassays specifically targeting designer amphetamine-like and synthetic cannabinoid drugs was collected from multiple published sources, and virtual chemical libraries for molecular similarity analysis were built. The virtual library for synthetic cannabinoid analysis contained a total of 169 structures, while the virtual library for amphetamine-type stimulants contained 288 compounds. Two-dimensional (2D) similarity for each test compound was compared to the target molecule of the immunoassay undergoing analysis.

Results

2D similarity differentiated between cross-reactive and non-cross-reactive compounds for immunoassays targeting mephedrone/methcathinone, 3,4-methylenedioxypyrovalerone, benzylpiperazine, mephentermine, and synthetic cannabinoids.

Conclusions

In this study, we applied 2D molecular similarity analysis to the designer amphetamine-type stimulants and synthetic cannabinoids. Similarity calculations can be used to more efficiently decide which drugs and metabolites should be tested in cross-reactivity studies, as well as to design experiments and potentially predict antigens that would lead to immunoassays with cross reactivity for a broader array of designer drugs.

Khat and synthetic cathinones: a review

For centuries, 'khat sessions' have played a key role in the social and cultural traditions among several communities around Saudi Arabia and most East African countries. The identification of cathinone as the main psychoactive compound of khat leaves, exhibiting amphetamine-like pharmacological properties, resulted in the synthesis of several derivatives structurally similar to this so-called natural amphetamine. Synthetic cathinones were primarily developed for therapeutic purposes, but promptly started being misused and extensively abused for their euphoric effects. In the mid-2000's, synthetic cathinones emerged in the recreational drug markets as legal alternatives ('legal highs') to amphetamine, 'ecstasy', or cocaine. Currently, they are sold as 'bath salts' or 'plant food', under ambiguous labels lacking information about their true contents. Cathinone derivatives are conveniently available online or at 'smartshops' and are much more affordable than the traditional illicit drugs. Despite the scarcity of scientific data on these 'legal highs', synthetic cathinones use became an increasingly popular practice worldwide. Additionally, criminalization of these derivatives is often useless since for each specific substance that gets legally controlled, one or more structurally modified analogs are introduced into the legal market. Chemically, these substances are structurally related to amphetamine. For this reason, cathinone derivatives share with this drug both central nervous system stimulating and sympathomimetic features. Reports of intoxication and deaths related to the use of 'bath salts' have been frequently described over the last years, and several attempts to apply a legislative control on synthetic cathinones have been made. However, further research on their pharmacological and toxicological properties is fully required in order to access the actual potential harm of synthetic cathinones to general public health. The present work provides a review on khat and synthetic cathinones, concerning their historical background, prevalence, patterns of use, legal status, chemistry, pharmacokinetics, pharmacodynamics, and their physiological and toxicological effects on animals and humans.